I don't see a way to import the cov_struct through the sm. api
it's not part of families, it's directly in genmod.
How should it be added? What should be the officially advertised import path?
from statsmodels.covariance import cov_struct?
from statsmodels.covariance import cov_struct
imported as sm.covariance.cov_struct through api.
ENH: Add api for covstruct. Clear __init__. Closes #1917.
(where's the link to the PR?)